The start of 2013 marks a significant milestone for the internet, as it is 30 years ago that Arpanet, precursor of the modern day internet, was switched to running on the TCP/IP protocol stack, a move that paved the way for the global internet as we know it today.

Arpanet, or the Advanced Research Projects Agency Network, was itself the world's first operational packet-switched network, and a product of the Cold War era. It was developed to link together the numerous computer systems and sites operated by the US military, to make it easier to access resources at one location from any other on the network.

However, a major hurdle that the scientists and engineers faced was that the equipment at different sites was sourced from different vendors, and hence a host of incompatible communications technologies and protocols were in use.

One engineer involved in the Arpanet project was Vint Cerf, who in commemoration has posted an article to Google's official blog. Cerf outlines the situation back then, and the need for a common protocol that could be used to join the disparate networks together.

"There was no common language. Each network had its own communications protocol using different conventions and formatting standards to send and receive packets, so there was no way to transmit anything between networks," he wrote.

Transmission Control Protocol, or TCP, was developed by Cerf and others to meet this requirement, and evolved gradually, eventually being split into two separate parts - TCP and the Internet Protocol (IP) - before settling into a stable implementation with IPv4, the version which is still largely in use today.

The official Arpanet switchover to TCP/IP was performed on 1 January, 1983, and went relatively smoothly, according to reports, with just a few sites experiencing difficulties as other protocols were turned off.

In 1984, the US Department of Defense made TCP/IP the standard for all military computer networks, which led to its increased adoption in research facilities and educational establishments, and also set it on the path to becoming a standard for commercial IT products.

With TCP/IP, Arpanet formed the core of the fledgling internet, although the Arpanet itself was formally decommissioned in 1990.

It is sobering to think that despite the introduction of IPv6, the vast majority of sites and systems on the internet are still using IPv4 - the same version of the protocol that was used when the switchover happened 30 years ago.